Real-Time Magnetic Resonance Imaging of Bubble Behavior and Particle Velocity in Fluidized Beds

Snapshots of particle concentration and velocity fields in bubbling gas-solid fluidized beds were acquired using magnetic resonance imaging. Using a recently developed multichannel radiofrequency receiver coil in combination with fast readout techniques, adapted from medical MRI protocols, the temporal resolution was 7 and 18 ms for two-dimensional images of particle concentration and velocity fields, respectively. A cylindrical bed with 190 mm diameter and 300 mm height was filled to heights of 100, 150, and 200 mm with spherical 1 and 3 mm diameter particles and fluidized at ratios of superficial gas velocity to minimum fluidization velocity (U/U-mf) of 1.2, 1.5, 2.0, 3.0, and 4.0. The effects of these varying parameters on the number of bubbles, bubble diameter, bed height, and particle speed are investigated. It is hoped that these data sets will become important benchmarks against which computational, analytical, and empirical models can be validated.